Function subarray

modules/llrt_buffer/src/buffer.rs:366–398

(
    this: This<Object<'js>>,
    ctx: Ctx<'js>,
    start: Opt<isize>,
    end: Opt<isize>,
)

    let source_bytes = ObjectBytes::from(&ctx, this.0.as_inner())?;
    let source_bytes = source_bytes.as_bytes(&ctx)?;

    if source_start > source_bytes.len() {
        return Err(Exception::throw_range(
            &ctx,
            "The value of \"sourceStart\" is out of range",
        ));
    }

    // sourceEnd is clamped (not an error), unlike sourceStart above.
    let source_end = source_end.min(source_bytes.len());

    let mut copyable_length = 0;

    if source_start >= source_end {
        return Ok(copyable_length);
    }

    if let Some((array_buffer, target_byte_length, target_byte_offset)) =
        target.get_array_buffer()?
    {
        let target_bytes =
            resolve_view_bytes(&ctx, array_buffer, target_byte_length, target_byte_offset)?;

        if target_start <= target_bytes.len() {
            copyable_length = (source_end - source_start).min(target_bytes.len() - target_start);

            target_bytes[target_start..target_start + copyable_length]
                .copy_from_slice(&source_bytes[source_start..source_start + copyable_length]);
        }
    }

    Ok(copyable_length)
}

fn subarray<'js>(
    this: This<Object<'js>>,